1. Field of the Invention
The present invention relates to a pad lock that assures reliable change of the code number.
2. Description of the Related Art
A typical pad lock 7 is shown in FIG. 6 of the drawings and includes an outer casing 71, a lock main body 72, and a shackle 73. The shackle 73 includes a longer section and a shorter section that are respectively received in two receptacles 720 in outer casing 71. The longer and shorter sections of the shackle 73 include aligned notches 731. The longer section includes a spring 732 mounted around a reduced end section 733 thereof that has a distal end 734 of a diameter greater than the reduced end section 733. The spring 732 bears against a retaining inner annular flange 711 in one of the receptacles.
The lock main body 72 is mounted in the outer casing 71 and includes a stem 721 slidably mounted therein. An end block 722 is threadedly engaged with a threaded end of the stem 721. Several number wheels 723 are rotatably mounted around the stem 721. Also rotatably mounted around the stem 721 are several retaining sleeves 725 each of which includes a key 726 releasably engaged with a toothed hole 724 of an associated number wheel 723 to rotate therewith. Each retaining sleeve 725 further includes an enlarged circular end with a circular section and a rectilinear section.
Two pin members 712 are mounted in the outer casing 71, and a spring 710 is provided to bias the pin members 712 to respectively engage with the notches 731 of the shackle 73 and thus retain the shackle 73 in a locked status.
A lever member 713 is mounted in the lock main body 71. The lever member 713 includes a first end 715 and a number of spaced tongues 716 formed on a second end thereof The second end of the lever member 713 further includes a positioning member 717 formed thereon.
If any one of the number wheels 723 is not in the unlocking position (i.e., the code number is not matched), at least one tongue 716 will bear against the circular section of the enlarged circular end and thus retain the first end 715 of the lever member 713 in a position between the pin members 712. Thus, the pin members 712 are moved outwardly to engage with the notches 731, respectively. The positioning member 717 is in a position that prevents from axial movement of the retaining sleeves 725 and the stem 721, as the positioning member 717 stops axial movement of the end block 722.
When all of the number wheels 723 are in the unlocking positions (i.e., the code number is matched), the tongues 716 bear against the rectilinear sections of the retaining sleeves. The first end 715 of the lever arm 713 disengages from the pin members 712 such that the shackle 73 moves upwards under the action of the spring 732 and thus disengages from the pin members 712. It is appreciated that the positioning member 717 is in a position that allows axial movement of the retraining sleeves 725 and the stems 721. If the user wants to set a new code number, he/she may insert an elongated member 80 (see FIG. 6) via an opening 718 of the outer casing 71 to move the stem 721 and the retaining sleeves 725 axially. The key 726 on each retaining sleeve 725 disengages from the associated number wheel 723 and thus allows free rotation of the number wheel 723. Thus, the user may set the number wheels 723 to the required new code number. The elongated member 80 is removed after setting of the new code number, and the retaining sleeves 725 and the stem 721 return to their initial positions under the action of a spring (727). The key 726 of each retaining sleeve 725 re-engages with the associated number wheel 723. Accordingly, the pad lock can be unlocked by a new code number from now on.
Referring to FIG. 7, the lower end of the spring 732 is inclined and thus may be stuck in the inner annular flange 711. In this case, the spring 732 might be twisted and thus looses its elasticity if the shackle 73 is forcibly turned when the lower end of the spring 732 is stuck.
Referring to FIG. 8, the shackle 73 might be tilted such that the enlarged distal end 734 of the shackle 73 exerts an axial force to the end block 722 of the stem 721. As a result, the code number of the pad lock could be inadvertently changed even if any one of the number wheels 723 is turned and the user is not aware of this situation.
Referring to FIG. 9, if the pad lock is in an unlocked status and if the leftmost number wheel 723 is inadvertently rotated and thus does not correspond to the correct code number, the associated tongue 716 is lifted such that the positioning member 717 is moved and thus cannot prevent axial movement of the stem 721 and the retaining sleeves 725. As a result, a change in the code number can be proceeded when the number wheels 723 are not in the positions corresponding to the correct code number. The user will be confused, as the number shown by the number wheels is not the correct code number after the code number changing procedure.
The present invention is intended to provide an improved pad lock that mitigates and/or obviates the above problems.